linux-kernel - [PATCH] kdb: Replace deprecated strcpy() with strscpy()

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Message-ID: <20250814120338.219585-2-thorsten.blum@linux.dev>
Date: Thu, 14 Aug 2025 14:03:37 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Jason Wessel <jason.wessel@...driver.com>,
	Daniel Thompson <danielt@...nel.org>,
	Douglas Anderson <dianders@...omium.org>,
	Nir Lichtman <nir@...htman.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Yuran Pereira <yuran.pereira@...mail.com>
Cc: linux-hardening@...r.kernel.org,
	Thorsten Blum <thorsten.blum@...ux.dev>,
	Daniel Thompson <daniel@...cstar.com>,
	kgdb-bugreport@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: [PATCH] kdb: Replace deprecated strcpy() with strscpy()

strcpy() is deprecated; use strscpy() instead and remove several manual
NUL-terminations.

Since the destination buffers 'cmd_cur' and 'cmd_hist[cmd_head]' have
the fixed length CMD_BUFLEN, strscpy() automatically determines their
size using sizeof() when the size argument is omitted. This makes the
explicit size arguments for the existing strscpy() calls unnecessary,
remove them.

No functional changes intended.

Link: https://github.com/KSPP/linux/issues/88
Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
 kernel/debug/kdb/kdb_main.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 7a4d2d4689a5..ea7dc2540e40 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -727,14 +727,10 @@ static int kdb_defcmd(int argc, const char **argv)
 	mp->help = kdb_strdup(argv[3], GFP_KDB);
 	if (!mp->help)
 		goto fail_help;
-	if (mp->usage[0] == '"') {
-		strcpy(mp->usage, argv[2]+1);
-		mp->usage[strlen(mp->usage)-1] = '\0';
-	}
-	if (mp->help[0] == '"') {
-		strcpy(mp->help, argv[3]+1);
-		mp->help[strlen(mp->help)-1] = '\0';
-	}
+	if (mp->usage[0] == '"')
+		strscpy(mp->usage, argv[2] + 1, strlen(argv[2]) - 1);
+	if (mp->help[0] == '"')
+		strscpy(mp->help, argv[3] + 1, strlen(argv[3]) - 1);
 
 	INIT_LIST_HEAD(&kdb_macro->statements);
 	defcmd_in_progress = true;
@@ -860,7 +856,7 @@ static void parse_grep(const char *str)
 		kdb_printf("search string too long\n");
 		return;
 	}
-	strcpy(kdb_grep_string, cp);
+	strscpy(kdb_grep_string, cp);
 	kdb_grepping_flag++;
 	return;
 }
@@ -1076,12 +1072,12 @@ static int handle_ctrl_cmd(char *cmd)
 		if (cmdptr != cmd_tail)
 			cmdptr = (cmdptr + KDB_CMD_HISTORY_COUNT - 1) %
 				 KDB_CMD_HISTORY_COUNT;
-		strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN);
+		strscpy(cmd_cur, cmd_hist[cmdptr]);
 		return 1;
 	case CTRL_N:
 		if (cmdptr != cmd_head)
 			cmdptr = (cmdptr+1) % KDB_CMD_HISTORY_COUNT;
-		strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN);
+		strscpy(cmd_cur, cmd_hist[cmdptr]);
 		return 1;
 	}
 	return 0;
@@ -1285,19 +1281,19 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
 		cmdbuf = kdb_getstr(cmdbuf, CMD_BUFLEN, kdb_prompt_str);
 		if (*cmdbuf != '\n') {
 			if (*cmdbuf < 32) {
-				if (cmdptr == cmd_head) {
+				if (cmdptr == cmd_head)
+					/* Copy the current command to the
+					 * history and let strscpy() replace the
+					 * last character with a NUL terminator.
+					 */
 					strscpy(cmd_hist[cmd_head], cmd_cur,
-						CMD_BUFLEN);
-					*(cmd_hist[cmd_head] +
-					  strlen(cmd_hist[cmd_head])-1) = '\0';
-				}
+						strlen(cmd_cur));
 				if (!handle_ctrl_cmd(cmdbuf))
 					*(cmd_cur+strlen(cmd_cur)-1) = '\0';
 				cmdbuf = cmd_cur;
 				goto do_full_getstr;
 			} else {
-				strscpy(cmd_hist[cmd_head], cmd_cur,
-					CMD_BUFLEN);
+				strscpy(cmd_hist[cmd_head], cmd_cur);
 			}
 
 			cmd_head = (cmd_head+1) % KDB_CMD_HISTORY_COUNT;
-- 
2.50.1